This invention relates generally to ultrasonic imaging and, more particularly, to creating multiple planar ultrasonic images of a volumetric region of the body in real-time.
A major advantage of three-dimensional ultrasonic imaging is the ability it provides to obtain unique image planes through the volume of an object such as a human body, image planes not available through conventional two-dimensional scanning. For example, through three-dimensional imaging techniques one can look simultaneously at several different cut planes of a region of tissue to thereby observe features from different angles or views. Alternatively, it may be desirable in certain instances to view an image plane at a constant depth below the object surface such as the skin. Such an image plane cannot be obtained with normal two-dimensional scanning because of the orientation of the ultrasonic probe relative to the object.
With the ability to acquire multiple image planes of a volumetric region comes the need to define the planes to be imaged, their relationship to each other in space, and the best way to display the images. In the past, a common display technique has been to display three ultrasound images of a volumetric region which are of mutually orthogonal planes. Each image has two orthogonal cross-hairs displayed over it, depicting the positions of the other two orthogonal image planes. As the cross-hairs are dragged to different positions, a new parallel image plane in that dimension is selected and displayed. These images have generally been static (non-real time) images which were reconstructed from a previously acquired volumetric echo data set. This display technique enables the clinician to survey and define tissue structures in a volumetric region by their appearances in intersecting image planes.
Such a display is useful for static image data of a volumetric region, which can readily be appropriately readdressed for display of different image planes as the selection cross-hairs are moved. The display technique does not lend itself to real-time imaging, as the complexity of control and display would be increased significantly for real-time imaging. Furthermore, such a real-time display can present too much information for the clinician to analyze in a methodical or organized manner. Hence there is a need for effective display and control of multiple real-time planar images of a volumetric region.
In accordance with the principles of the present invention, method and apparatus are described for creating and displaying multiple planar images of a volumetric region of the body. In one aspect of the invention, two real-time image planes are acquired and displayed in what is referred to herein as a xe2x80x9cbiplanexe2x80x9d display format. The two planes of the biplane display can be controlled in two control modes, one in which an image plane is tilted relative to another image plane, and another in which one image plane is rotated relative to the other. As an image plane is tilted, the appearance of the icon changes correspondingly. In an illustrated embodiment the icon represents the outline of a sector image, the aspect ratio of which changes as the tilt control is manipulated.